1. Field of the Invention
The present invention generally relates to the packaging art and more particularly to tensioning hoops of the type surrounding a container and providing for a releasable connection of the container with a lid. Further, the invention relates to a method for closing a container with a lid by means of a tensioning hoop having a releasable closure or actuating means.
2. Description of the Art
Conventional barrels or drum-type containers for packaging, transporting and storing of liquids, pastes or particulate solids and the like goods are normally made of a relatively thin wall material, e.g. sheet metal, paper board or the like, and provided with a relatively large aperture. In order to increase the stability of the apertured container portion, a rim portion, e.g. constituted by an outwardly extending bead formed or rolled in the container wall material, is provided around the container aperture. A lid substantially matching the container aperture is used for closing the container and normally has a peripheral rim extending over the container aperture. Frequently, the lid rim is provided with a continuous recessed portion or groove provided with a sealant or elastic sealing member for contact with a surface portion of the rim of the container aperture.
A well known means for securing the lid on the container is a tensioning hoop or ring for surrounding both the lid and the aperture rim and having two pressure surfaces in a mutually wedge-like arrangement. One pressure surface of the hoop engages the outer lid rim portion while the other pressure surface engages the rim or bead of the container aperture.
For repeatedly closing and opening the container, one conventional type of the tensioning hoop is provided with a radial gap or slot portion bridged by a "snap means" in the form of a connection between the hoop ends at both sides of the slot that permits to tension or to release the hoop, i.e. a hoop actuating device. In a first or closing position, the gap width controlled by the actuating device is relatively small, e.g. a fraction of an inch, and the tensioning hoop is "contracted" so that its pressure surfaces are in a firm engagement both with the lid and the rim of the container aperture.
In a second or opening position, the gap width as set by the actuating device is relatively large, e.g. an inch or more, and the tensioning hoop is "expanded" so as to permit removal of the lid from the container aperture.
The snap or actuating means, e.g. a conventional pivotable latch arrangement, can be operated for alternatingly contracting the hoop (slot in closing position) and holding it in its contracted and lid-securing position, and for expanding the hoop (slot in opening position) to permit removal of the lid.
Such a conventional tensioning hoop has several draw-backs: The prior art latch arrangement protrudes substantially from the outer hoop periphery and virtually precludes automated closure of a container that has been filled in an automated packaging machine and is supplied with lid plus hoop. Manual operation of the snap latch is required; further the tensioning hoops cannot normally be stacked for easy supply at the packaging station. Also, the protruding structure of the snap latch complicates transport and storage of the closed containers and may be quite hazardous for the operator. Last but not least, conventional snap-latches for tensioning hoops consist of a plurality, typically about six, components and require separate assembly of the latch and subsequent mounting thereof on the tensioning hoop, e.g. by spot-welding, rivetting and the like.
Accordingly, a main object of this invention is to provide for an improved tensioning hoop in which the hoop actuating means has a simplified yet fully effective structure and does not substantially protrude from the periphery of the hoop.
A further object of the invention is an improved method for sealingly closing a container with a lid using a tensioning hoop that avoids the necessity of manual operation in the use of such container for automated packaging of goods.
Further objects will become apparent as the specification proceeds.